Two problems related to check engine light on have been reported for the 2003 Ford Expedition. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Ford Expedition based on all problems reported for the 2003 Expedition.
Check engine light came on while driving home and the engine shut down 4 times each time the battery would die instantly. We had to keep jump starting it to get home. 2 days later the check engine light started flashing. Scanned it came back p0304 cylinder 5 misfire. Changed spark plugs and coils. Engine light went off. Ran obd2 scanner to double check codes. Code p2503 charging system low voltage . Took battery to advanced auto parts had them test it. The coca should have been 650cca and was at 11cca so bought a new battery. Next day took son to school less the 2 miles ran fine on my way home it died 3 times this time I would wait a few minutes then restart it. Check engine light never came on started searching on line and and calling mechanics. So bought new alternator. Started the truck to warm up after 5 minutes it shut down again waited a minute and started back up did it again. This time the battery light came on. So after searching many people were saying the fuseable link was bad so went to Ford had one ordered installed it to day. Battery light still on started it ran for 5 min and died again. So now I bought new spark plugs, coil packs, battery,alternator, fusible lin. Now obdii code b1676- battery pack voltage out of range tester battery fully charged tested alternator it's at 14. 7 which it supposed to be.
A month or so ago the truck started running rough and engine light came on. It turns out it was spark plug #4 misfiring. Replaced it and all was golden until yesterday (4/3/12) when I heard a loud pop upon starting the truck and then it was idling rough. Check engine light came back on and spark plug #4 is misfiring again. We bought this truck used and it's been one thing after another. So disappointed in Ford. Hope they address this issue and due the proper thing.